It has been recognized for many years that the use of hydrogen gas as a primary fuel, supplemental fuel, or fuel additive, either alone in addition to petroleum base fuels offers distinct advantages for the operation of internal combustion engines, particular in light of increased fuel costs, limited supplies, and environmental concerns. The hydrogen gas not only provides fuel efficiencies and economies, but when used with petroelum base fuels also inherently causes them to burn more completely, thus minimizing and at times completely eliminating the contaminating pollutants in the gases exhausted to the atmosphere.
The main effort towards the development of practical usage of hydrogen as a fuel for internal combustion engines has been by way of the storage of hydrogen gas on board the vehicle as the primary fuel source. The most prominent method used for the storage of the gas has been the utilization of various types of metal hydrides, which act as hydrogen gas sponges to absorb and release the gas as required.
Several large business entities such as Brookhaven Labs, Billings Corporation, and Mercedes Benz have adopted such on-board hydrogen storage techniques, however, while such techniques are attractive for many internal combustion engine applications there remains the problem of converting engines to those primarily operated by hydrogen fuel and the problems of distributing hydrogen to the consuming public. For these reasons, it is felt that such an approach is years away from implementation on a commercial scale.
Further, approaches which involve the on-board storage of hydrogen are not initially attractive to a large portion of the users of internal combustion engines, because hydrogen is considered dangerous to store and handle.
Considerable further efforts have been expended toward utilizing hydrogen as a supplemental fuel which may be generated on board in small amounts and used immediately, so that the storage problem does not exist. One such approach deals with heat recovery from the engine exhaust manifolds to drive various types of closed cycle engine loops, which in turn are used to provide a low voltage DC power source required for electrolysis cells which will generate hydrogen from a water source. The major problem with the electrolysis approach is that a very large electrical wattage is required to reform the water into its constituent elements, and the amounts of such energy which can be generated from the exhaust manifold heat has, for the most part, proven insufficient to provide an ample flow of hydrogen. Therefore, these approaches generally require additional sources of electrical energy in order to be operative, and such additional sources of energy (such as additional batteries) are extremely expensive.
Another on-board hydrogen generation technique is the reforming of gasoline in which a small flow volume of gasoline is broken down into its basic components in a thermal reactor, with hydrogen gas produced along with varying amounts of hydrocarbon by-products. While prototypes have been developed, extensive size reduction and improvement will be necessary before commercialization is realized. Further, such approaches are inherently disadvantageous in that a portion of the petroleum fuel, which is attempted to being saved, is utilized in the reforming process and therefore lost as the primary fuel.
Another approach to the on-board generation of hydrogen is the steam-over-iron process, in which water is transformed into steam, and then passed over iron flakes or filings. The iron filings tend to remove the oxygen gas from the steam by an oxidation process, leaving the hydrogen gas for usage as a fuel or fuel supplement. Examples of this approach are described in the patents to Harrel, U.S. Pat. No. 1,966,345 and Kelly, U.S. Pat. No. 4,256,060. It is recognized in both of these patents that periodic cleaning or changing of the iron flakes or filings is necessary in order to keep this technique operative.
In general, prior art disclosures indicate that the engine exhaust heat alone is either insufficient, cannot be kept hot enough, or enough heat therefrom cannot be transferred to the water to liberate hydrogen therefrom. Of all prior art references known to applicant concerning the on-board generation of hydrogen, only two have been located with are directed to the generation of hydrogen from water utilizing primarily a direct heat exchange process. These references are U.S. Pat. Nos. 4,030,453 to Sugimoto, and 4,380,970 to Davis. In the Sugimoto disclosure, the water undergoes a three step heat exchange process, with the final step of the heat exchange taking place in the engine block itself. Thus, a complete redesign of the engine block is necessary and from a commercial standpoint is not likely to receive immediate widespread acceptance. The Davis patent also utilizes a quite complicated technique in which there is provided a disassociation chamber in the form of a transition tube carrying a copper spiral ribbon adjacent the engine manifold through which the water (or steam passes) in order that it be heated sufficiently to disassociate to its constituent gases hydrogen and oxygen. This also is a relatively expensive undertaking involving considerable changes to the engine itself and cannot be easily implemented.
In order to realize early and wide range acceptance, it is believed that a system utilizing hydrogen as a supplemental fuel or fuel additive must be relatively inexpensive; be capable of retrofitting existing engines; be compatible with internal combustion engines without substantial alteration of the engine or engine block; be capable of on-board generation of hydrogen, and the hydrogen must be generated by means of a heat exchange technique.